Gas producing charge



United States Patent 3,033,716 GAS PRODUCING CHARGE Ralph F. Preckel,Cumberland, Md., assignor to Hercules Powder Company, Wilmington, DeL, acorporation of Delaware No Drawing. Filed Mar. 7, 1955, Ser. No. 492,80218 Claims. (Cl. 149-96) This invention relates to the production ofsmokeless powders and more particularly to the production of smokelesspowders having peculiarly desirable ballistics for applications injet-actuated devices.

It is well known that there is a definite and direct relationshipbetween the pressure at which a smokeless powder propellant burns andits burning rate. This relationship may be mathematically expressed asr=cp or as log r=n log P+log c, where r is the burning rate, P is thepressure at which the burning rate is measured, and c and n areconstants characteristic of a given propellant. Thus, when a plot of logr against log P is made for the conventional propellant, a straight lineof slope n is obtained showing an increase in burning rate for eachincrease in pressure. Such a relationship is not disadvantageous in theconventional propellant and in fact is used to advantage in progressivepowders where it is highly desirable to generate increased pressuresafter the projectile or shot charge has begun to move along the barrel.However, this relationship presents a serious problem in formulation ofpropellants for jet-actuated devices since once the desired operatingpressure is reached, totally different considerations obtain.

It is highly desirable, once the operating pressure of a jet-actuateddevice is reached, that the pressure gen erated by the burningpropellant be maintained as nearly constant as possible. Accordingly, ifthis result is to be attained, the slope n of the line representing thepressure-burning rate relationship of the particular propellant mustdesirably approach zero in the zone of useful rocket pressure. In theprior art rocket powders, in all of which the slope n has a value of 0.7or over, any fracturing or slivering of the propellant charge leads to apressure build-up because of an increase in linear burning rateresulting from the increase in pressure due to the increase in burningsurface. The higher the 11 value of the particular powder, the higherwill be the pressure rise encountered. Therefore, the results of such afracturing or slivering vary from a highly undesirable thrustfluctuation with consequent aberration in ballistics, to actual failureof the jet device if, with a propellant of high n value, the pressurebuild-up is excessive. Even unusual roughness of the charge causesserious changes in burning pressure and burning rate in the presentlyavailable rocket propellants with the result that errors of 1% in thenozzle diameter have been found to build up to an aberration of 5% ormore in ballistics. Consequently, with the propellants now available,there is very little allowable tolerance in manufacture of charges andnozzles for jet devices. A propellant having a very low n value withinthe range of useful rocket pressures, however, would allow forconsiderable tolerances without appreciable deviation from the specifiedballistics.

A second serious problem confronting producers of propellants forjet-actuated devices is the diminution of the temperature coefiicient ofequilibrium pressure at the desired operating pressure or pressurerange. The temperature coefficient of equilibrium pressure is a measureof the pressure variation to be expected on account of temperaturevariation alone, using a given propellant. It is obtained by firingidentical samples of propellant under identical conditions except forchanges in temperature and pressure. The coefiicient may be expressed as3,033,716 Patented May 8, 1962 where AP is the experimental dilferencein pressure under conditions of equilibrium burning due to thetemperature change At; and 1 is the mean of the low-temperature andhigh-temperature pressures.

The advantage of having a low-temperature coeflicient of equilibriumpressure is obvious. If the coefiicient is low, the jet-actuated devicemay be designed for an unusually low range of service pressure over thewide temperature range ordinarily specified for such devices in fielduse. Since existing propellants generally have temperature coefiicientsof equilibrium pressure of about 0.8%/ C. or more, service pressure maychange by 100% or more in going from the lowest expected temperature(about -60 C.) to the highest expected temperature (about 50 C.). It istherefore highly desirable to lower the temperature coefficient ofequilibrium pressure below that of existing rocket propellants andthereby hold variation in service pressures due to temperature change toa minimum. If the coefiicient could be lowered from 0.8%/ C. to 0.4%/ C.or less, service pressure variation would be diminished by at leastone-half.

As a result of the advantages set forth above for a propellant having alow n value and a low temperature coeificient of equilibrium pressure,the combination of those two ballistic characteristics would allowadditionally for important economies in the inert weight of jetactuateddevices. This is clearly seen if the equation is examined which relatesthe ratio between the mass of propellant (m) and the mass of the jetdevice without propellant (M), the gas velocity of the burningpropellant (V), and the highest theoretically obtainable velocity of thejet device (V as follows:

With propellants now available, the highest ratio or m/M has been about1, where mass of propellant and mass of jet device are about equal. Ifit is possible, by use of a new propellant which will not build upexcessive pressures, to decrease M by 10% and increase the amount ofpropellant to give the same total initial weight, V would be increasedby a factor of about 1.15. This would be a 15% improvement.

Therefore, an object of the present invention is the production ofpropellants for jet-actuated devices which are characterized by such aburning rate-pressure relationship that substantially constant or morenearly constant burning rates are maintained throughout a wide pressureregion within the range of useful rocket pressures.

It is a further object of this invention to produce a propellant forjet-actuated devices which is characterized by a lower temperaturecoeificient of equilibrium pressure which will minimize variation ofservice pressure due to temperature.

Generally described, the present invention comprises gas-producingcompositions which comprise a smokeless powder having uniformlyincorporated therein and intimately admixed therewith within eachparticle thereof a minor amount of at least one material selected fromthe group consisting of lead, the oxides of lead, the inorganiccompounds of lead and the aliphatic compounds of lead, said compositionshaving a heat of explosion of not more than about 900 calories per gram.The smokeless powders to which these ballistic modifiers are added maybe of either single or multiple base. If the smokeless powder to whichone or more of the ballistic modifiers is added is a single-base powder,it should preferably comformulations to which the modifiers have notbeen added, and to show the lack of an appreciable effect of themodifiers on powers having a heat of explosion in excess of about 900calories per gram. It will be noted that in Z mtroclellluiose i from 5most instances where the value of n remains high (0.7 or ijfig g' h e ian r ,2; 0.8 or above) between pressures of 300 and 5000 pounds s 0 Preera y compn e m per square inch, no value is recorded for Pressureregion 85% mtrocenulose from 10% to 35% of exploswe of lowest n sincesuch formulations are unsatisfacto liquid ester, and from to 30% of asubstantially non- U ml th di t d th d m n volatile nonexplosiveplasticizer. In any formulation, h ess lerwlse m ca 6 a g T co p051 0however, it is critical that the heat of explosion of the ade exam! werePrepare y t C so vent Process ditive system be not greater than about900 calories per er described. gram. Propellants prepared according tothis invention The indicated amounts Of the baulStlC modifiers 1n thewhich contain a minor amount f th b v -li ted following table were addedto a standard rocket powder modifiers and which have a heat of explosionwhich does composition having the following composition: not exceedabout 900 calories per gram, will be characterized by a pressure-burningrate relationship having a Nitrocellulose (13.15% N) 58.5 substantiallylower n value and a substantially lower tem- Nitroglycelin 22.5 peraturecoetficientally of equilibrium pressure. More- Triacetin 5 over, maccordance with the invention disclosed and Ethyl centralite claimed incopending application Serial No. 492,801, filed Dinitrotoluene 2 5 March7, 1955, it has been discovered that by addition Table I ModifierTempera- Pressure ture coefii'i- Heat of region of cient of Exampleexplosion, Lowest n lowest 11. pressure in Type Amount, caL/g. p.s.i.region of percent lowest 5.,

percent/"O.

No addition 700 0. 7 0- 8 Lead 0. 5 700 0. 0 1, 300-2, 300 0. 3 do 1. 0695 0. 2 1, 000-2, 000 0. a do 2. 0 685 0. 2 900-1, 900 0. 4 Leadmonoxide O. 5 700 0. 0 700-1, 200 O. 3 Lead oxide (red) 0. 5 700 0. 0700-1, 200 0. a Lead ermdda 0. 5 700 0. 0 600-1, 200 0. 3 Lead stearate.0. 1 700 0. 1, 450-2, 250 0. 6 da 0. 2 695 0. 20 1. 400-2, 350 0. a dd0. 4 690 0. 20 1, 200-2, 200 0. 3 d0 1. 0 675 0. 0 1, 000-1, 500 0. 5(10 2.0 650 0.0 700-1, 0 0.3 (in 4. 0 600 0. 0 700-1, 300 0. 4 Leadhydroxide 1. 0 695 0. 0 500-1, 000 0. 2 Lead dlacety 1.0 675 0. 0700-1,000 0. 5 do 2. 0 645 0. 1 500-1, 000 0. 4 Lead molybdate 1. 0 6950. 1 1, 0004, 700 0. 4 d0 2. 0 685 0. 0 900-1, 500 0. a Leadsiilfirin 1. O 695 0. 1 1, 100-1, 700 0. 3 Lead acetate- 1. 0 685 0.1620-1, 40 0. 5 Lead lii'inloafn 1. 0 685 0. 1 700-1, 600 0. a Basic ieadcarbonate (PbCO -Pb(OH)2) 1. 0 695 0. 2 700-1, 200 0. 5 Lead 0leate 1. 0685 0. 2 700-1, 200 0. 5 (in 2. 0 645 0. 3 700-1, 300 0. 5 Leadnaphthenate (metal concentration 24%)- 2. 0 680 0. 2 700-1, 300 0. 5Lead chloride 1. 0 695 0. 3 900-1, 500 0. 4 Lead emomare 1. 0 695 0. 3500-1, 200 0. 5 Lead iodide 1. 25 690 0. 4 300-1, 500 0. 6 Lead fluoride1.0 695 0. 4 700-1, 300 0. 5 Lead bromide 1. 0 695 0. 5 1, 300-2, 900 0.4 Lead diirare 1. 0 695 0. 5 1, 350-2, 400 0. 4 Lead oxalate. 1. 0 6950. 5 900-2, 000 1. 0 (l0 2. 0 685 0. 3 800-1, 650 0. 5 Lead tartrafe 1.O 690 0. 4 1, 300-1, 700 0. 7 d0 2. 0 675 0. 4 650-1, 500 0. 6 Leadazide 1. 5 695 0. 2 260 0. 7 do 1.5 695 0.2 270 0.5 Lead tetraethyl 2. 5662 0. 0 500-1, 100 0. 2 do 2. 0 621 0. 3 740-2, 100 0. 5

1 0.2%Zcarbon black added to composition.

of finely divided carbon to the compositions of the present invention,the burning rate of the composition can be Table 2 desirably increasedin the pressure region of low It value. It has been found that up to 10%of the various operable E additives may be employed without adverselyaffecting xafiple Exgffllple g the ballistics of the gas-producingcompositions of the invention. However, it is preferred to employ onlysuf- Nitmcenolose (mm N) 5 58 5 58 5 ficient of the additive to eflectthe desired modification gi yc ril 22.8 22.5 22.5 in ballistics. In mostcases it has been found that 2% ;,g:, 3;, 3;; of the various additives,based on the weight of the fig g eg 8-5 12.5 3.1 1

S eara e a smokeless powder employed, 1s p Heat olexploslon (cal 700 595Having now generally described the invention, the 1 0.7 0.7 0.0following examples are given to illustrate several formugi gg gi fig gjg 'fi lations incorporating varying amounts of the various bal- 7 regiono owest 0 (per tP 5 0.4

listic. modifiers, to compare these powders to similar Table 3 Table 6demonstrates that the desired modifieation in E 1 E 1 ballistics may beobtained in multiple-base powders con- 9. am x mp 6 6 taimng a hquidexplosive other than mtroglycerm.

In addition to the previously shown double-base powder examples, the nvalue and temperature coefficient of equiptii i ei tralig'Ii II 110 110librium pressure may be substantially lowered in powders o 0 one 00Leall g of smgle-base formulae, m which the only high potential ff 3 3 3g ingredient is nitrocellulose, plasticized with small percent- Pressureregion of lowest 11 .s.i.)--. 700-1, 200 10 ages of triacetin and ethylcentralite. Temperature coefiicient of pressure in region of lowest 11(perceut/ O.) 1. 0 0. 4

Table 7 Table 4 Example Example 15 Example Example Example Example 45 4656 57 58 59 57.0 60.0 Nitrocellulose (12.6% N)-, 90. 0 89. 0 93.0 92. 015.0 20. 0 Triacetin 9.0 9.0

1. 0 l. 0 Ethyl centralite-.-. 1. 0 1. 0 7. 0 7.0 6. 4 2.0 1. 0 1. 0 ylp20. s 11. 0 700 e70 e90 670 Lead stearate (add)- 0. 5 0. 7 0. 45 0. 7 04 Heat of explosion (cal. 570 62 Lowest 'n 0.7 0 n (p.s.i.) 2, 500-5,0002, 000-5, 000 Pressure region of lowest at (p.s.i.) 1, 200-2, 100Temperature eoelficient Temperature eoefiicient of pressure in region ofof pressure in region of lowest 11 (percent/ 0.) 1. 0 0.5 lowest 11(pereent/ O.).. o. 9 0.2 0. 8 o. 2

Table 5 Example Example Example Example Example Example 47 48 49 50 5152 Nitrocellulose (13.15% N) 58. 5 58. 5 58.5 58. 5 60. 0 53.0itroglycerin 22. 5 22. 5 22. 5 22. 5 30. 0 43. 0 Triaoetin--. 18. 0 18.0 8. 5 8. 5 9. 0 D iethylphthnl are 3. 0 Ethyl r'PnfralitA 1.0 1.0 8.08.0 1.0 1.0 Dinitrotoluono 2. 5 2. 5 Lead stearate (add) 0.5 0. 5 2.0 20 Magnesium stearate--- 0. 5 Heat of explosion (caL/g.) 745 735 690 690970 1, 150 Lowest 'll. 0. 7 0. 0 0.2 0. 7 0.5 0. 8 Pressure region oflowest 11 (p.s.i. 1,000- ,000 MOO-2,000 300-900 Temperature eoeflieientof pressure in region of lowest 11 (percent/ O.) i 0.8 0.3 0. 3 0. 9 0.72.0

In Table 5, Example 47 demonstrates the inability of mag- *Unplasticizednitrocellulose systems, containing only nesium stearate to produce thedesired modification in stabilizer and ballistic modifier, also show asubstantial ballistics, While pl 48 P 49 illustrate the P lowering in 11value and temperature coefiieient of equiablhty Of 1116 modlfiefs 111the hlghel' P P librium pressure as demonstrated in the following table.

Table 6 Table 8 Example Example Example 53 54 55 Example Example ExampleExample Nitrocellulose 12.67 N).-. 60 0 60. 0 70. 0 Diethylene gly eol(1511mm 25. o 30. 0 Nitrocellulose (12.6% N)... 99. o 91. 0 94. o 89. oTriethylene glyeol dinitrat 29. 0 55 thyl centrallte 1 0 1.0 1. 0 1. 0Glycol diaeetate 11. 5 9. 0 Lead stearate (add) 8. 0 Dinitrotoluene. 2.5 Lead metal pqW r d)-- 5. 0 10.0 Ethyl centralite.. 1 0 1. 0 1. 0 Heatof explosion (cel.lg.)-. 905 670 855 810 Lead, stearate (add) 1. 0 1. 0LOWOSlS 77.--- 0. 8 0 0. 35 0. 3 Heat of explosion (cal./g.).. 685 740825 Pressure region of lowest '11, Lowest n o. 7 0.1 0. a p.s.1.) 1,300-2, 500 650-2, 000 600-2, 000 Pressure region of lowest '11.(p.s.i.)... 900-1, 700 1,100-1, 700 Temperature coefiieient ofTemperature coelficient of pressure 60 pressure in region 01 in regionof lowest 11 (percent/ 0.). 1. 6 0. 3 0. 4 lowest n (percent/ 0.)... 1.3 0. 4 0. 5 0. 4

Table 9 Example 65 Example 66 Example 67 Example 68 Nitromllnlosn 58 558.5-. 58.5-- Nitroglymrin 27 0 27.0- 27 0 Triaeetin- 8 5 8 5 8.5--Ethyl centralite.- 2.0.- 2.0.. 2.0.. Ballistic modifier 4.0 lead2-ethyl- 4.0 lead 2-ethyl- 2.0 lead 2.0 tribasie lead hexoate. hexoate.perchlorate. maleate. Carbon black (added) 0. 0.2. Heat of explosion(caL/g.) 820 807 86 825. Lowest n. -0.38- 10 0.17-- -0.21-.---..---.--0.00. Pressure region of lowest 71 (p.s.i.) 300-500 1,050-2,0009004,3175 1,7002,300 7504,3541. Temperature coefiieient of pressure inregion of lowest 11 (percent/O.) 0.30 n 10 0.20 0.00. 0.36.

From the foregoing examples it is evident that although all of theballistic modifiers disclosed are operable, some are more effective thanothers in lowering the n value or the temperature coefiicient ofequilibrium pressure of a given propellant. This fact allows for a widechoice of modifier based on economic considerations as well as theballistics desired for a particular application. From the combinedviewpoints of eflfectiveness and economy, powdered lead, powdered leadoxides, and lead stearate are preferred.

While the ranges given for the conventional components of the singleormultiple-base powders are not critical as long as the heat of explosionof the powder with the added modifier does not exceed 900 calories pergram, it has been found that powders prepared according to these rangesare more apt to come within this critical calorific requirement.

The compositions of the invention may be prepared by solventlessextrusion. In the conventional solventless process, water-wetnitrocellulose and other ingredients are admixed in a Schrader bowl withwater. The resulting slurry or paste is dried to 10% water and iscolloided and dried between hot colloiding rolls which may be evenspeedor differential-speed rolls as desired. The resulting colloided, drysheets are then cut into disks or convolutely rolled into carpet rolls.The disks or carpet rolls are then extruded to desired grain size. Flakepowder may be formed by suitably shredding the sheet. The resultinggrains are normally glazed, usually with graphite, to lower staticgeneration and to improve flowing characteristics.

The compositions of the invention may also be made by the solventprocess. In the usual solvent process, the water in hydratednitrocellulose is first replaced, for example, by treatment with ethylalcohol. A colloiding solvent such as ether or acetone is then added tothe dehydrated nitrocellulose along with additional ingredients and adoughy mass is formed in a suitable mixer such as a sigma blade mixer.This dough is then formed into green grains, usually by extrusion intocords and cutting the cords to the desired length. The green grains arethen subjected to solvent removal steps. The greater portion of thesolvent is normally removed by passing a warm inert gaseous medium suchas air or flue gas over the grains. The remainder of the solvent whichcan be practically removed is then usually leached out by a watertreatment. Water is then removed by an air dry step and the dry grainsare normally given a glaze, usually of graphite, to lower staticgeneration and to improve flowing characteristics.

As is well known in the art, colloiding solvent can be removed frompowder grains of large diameter and Web only with extreme difliculty.This difiiculty increases as the web thickness is increased. It is,therefore, desirable to prepare grains of the multiple-base formulationsof this invention by solventless extrusion or by a suitable castingprocess. It is preferred to extrude grains up to about or 6 inches indiameter and to cast all larger grains. Casting of the larger grains ispreferred because the cost and massive nature of extrusion presses largeenough to produce grains of over 5 or 6 inches in diameter becomeprohibitive.

[In the usual casting process, tiny singleor doublebase powder grains,prepared by either the solvent or solventless techniques, are introducedinto a mold together with suitable plasticizers. The plasticizers causethe grains to coalesce into a unitary mass of plastic composition. Thepreferred casting process is that disclosed in the copending applicationof Gordon W. McCurdy, Serial No. 28,218, filed May 20, 1948.

The single base formulations given in the examples are preferably madeby a conventional solvent process, extruded and cut to the desiredgranulation. Such a process limits the possible size of the single-basegrains to a diameter or web thickness which will allow suflicientremoval of the colloiding solvent. Grains of solvent-colloided powderhaving large diameter and web are, of course, operable and as along asthe heat of explosion does not exceed about 900 calories per gram,addition of the disclosed modifiers according to this invention willeffect the desired modification in ballistics. It is, of course, wellknown that the change in ballistics duning storage caused by gradualmigration and evaporation of the colloiding solvent is the reason whylarge grains of solvent-colloided powder are not manufactured. Asimproved processes and means for solvent removal are devevloped, it willperhaps be possible to produce correspondingly larger grains ofsolvent-colloided powder which are ballistically stable.

It is not preferred to produce single-base grains by solventlessextrusion or by casting because, in order to keep the powder in thesingle-base category, the plasticizer employed to bring about colloidingand/or consolidation must be of lower potential than the nitrocellulose.The necessary amount of plasticizer, therefore, so lowers the potentialthat such powders have only a limited application. Nevertheless,incorporation of the disclosed modifiers in single-base grains preparedby solventless extrusion or by casting still results in a low n valueand a low temperature coefiicient of equilibrium pressure.

If the gas-producing charges of this invention are made by solventlessextrusion, the ballistic modifier or modifiers are preferably added atsome time prior to dehydration of the water slurry and the additivesystem is mixed to a state of homogeneity. The slurry is thendehydrated, the moist mass is rolled into colloided sheets, the sheetsare made into rolls and the rolls are extruded in the conventionalmanner. However, it is often found adavntageous to add the ballisticmodifiers during the rolling operation, rather than to the water slurry.The modifiers are then intimately admixed throughout the compsoition byaction of the rolls. If the well known Schrader process is employed, themodifiers may be added to the hydrated nitrocellulose in the mixing bowlin any preferred order. A portion of the water is evaporated prior torolling. The Schrader process is preferred when water-solubleplasticizers are employed.

If the charges of this invention are prepared by solvent extrusion, theballistic modifier or modifiers are preferably added to the dehydratednitrocellulose after it has been broken up in a mixer. The modifiers maybe introduced with the plasticizer or plasticizers or may be addedbefore or after introduction of the plasticizer as may be desired in theparticular formulation.

If the grains are made :by casting, the ballistic modifier ishomogeneously incorporated during the preparation of the casting powderas above described.

In order to produce the plateau type ballistics of the invention, themodifiers must be uniformly incorporated with the other ingredients ofthe composition; that is, the modifiers must be intimately admixed withthe other ingredients within each particle of the composition whetherthe charge is a loose charge of individual grains or consists of asingle grain of any desired size. The glazing or coating of a singlegrain or a plurality of grains in a loose charge will not produce thedesired modification in the pressure-burning rate relationships. Thus,powder grains coated or glazed with a lead compound to render themfree-flowing are not operable in the invention.

The heat of explosion of an explosive composition may be experimentallydetermined in the known manner by actually exploding a sample of thesubstance in a bomb calorimeter under conditions which insure completecombustion of the constituents of the composition, and measuring theheat liberated. However, in the case of smokeless powder compositionswhich contain at most only small portions of inorganic material, it isusually desirable to determine the heat of explosion by calculation. Thecalculation of heats of explosion is especially desirable in order topredetermine the calorific value of a proposed composition prior to itsformulation. In this calculation, use is made of a simple relation;namely, the heat of explosion per gram of powder is equivalent to thesum of the products of the weight fraction of a given constituent by thecontribution to the heat of explosion of the constituent. Thiscontribution of the constituent is for convenience termed the partialcalorific potential or the partial heat of explosion, and is usuallydesignated as K. Thus, the heat of explosion of the composition isderived by the equation:

Heat of explosion=2X,K

where X, is the weight fraction of the powder component i.

For compositions consisting principally of carbon, hydrogen, oxygen, andnitrogen, K is quickly and accurately determined according to followingequations:

where O, is the number of gram-atoms of oxygen per gram of the powdercomponent i, C; is the number of gram-atoms of carbon per gram of thepowder component, i, H, is the number of gram atoms of hydrogen per gramof the powder component, 1', HQ is the heat of combustion at 25 C. andconstant volume, and AEf is the heat of formation per gram of the powdercomponents i from its elements.

Partial heats of explosion for inorganic substances, such as theballistic modifiers of the invention, are not quite so easily calculatedbut may be determined according to methods disclosed by De Pauw in Z. f.ges. Schiessund Sprengstotfwesen, 32, 11, 36, 60 (1937); or byHirschfelder and Sherman in Simple Calculation of ThermochemicalProperties for Use in Ballistics, 0.S.R.D. Report No. 1300, declassifiedand issued as PB27421S.

Actually, it is unnecessary to experimentally deter mine the K, valuesfor the various constituents of the smokeless powders in accordance withthe invention since tables of the partial heats of explosion for thesematerials are available as published data. The following is a listing ofthe K, values of the normally used smokeless powder components and manyof the operable ballistic modifiers in accordance with the invention.

Substance (i): Partial heat of explosion (cal/g.)

Acetone --l938 Carbon black 3330 Diamylphthalate -2190 Dibutylphthalate-2055 Diethanol nitramine dinitrate +:1294 Diethylene glycol dinitrate+1030 Diethylphthalate --1746 Dinitrotoluene l'40 Diphenylamine -2684Diphenylurea +2227 Diphenylurethane -2739 'Ethyl alcohol -1749 Ethylcentralite 2398 Ethyl urethane +1639 Graphite -3377 Lead Lead acetate-282 Lead azide +385 Lead bromide +137 Lead carbonate (basic) 47 1 Leadchloride --151 Lead chromate +977 Lead diacetylacetonate --868 Lead2-ethylhexoate 11336 Lead fluoride 127 Lead hydroxide 189 10 Substance(i)-Con. Partial heat of explosion (cal./ g.) Lead iodide --91 Leadlinoleate 1982 Lead molybdate +403 Lead naphthenate 2048 Lead oleate--2010 Lead oxalate +58 Lead oxide (PbO) +67 Lead oxide (Pb O +139 Leadoxide (PbO +302 Lead stearate -2800 Lead sulfate -15O Lead sulfide --222Lead tartrate 172 Lead tetraethyl 123l Nitrocellulose, 13.25% N +1041Nitrocellulose, 13.15% N +1027 Nitrocellulose, 13.00% N +1007Nitrocellulose, 12.60% N +951 Nitrocellulose, 12.20% N +895Nitrocellulose, 12.00% N +867 Nitrocellulose, 11.50% N +797Nitroglycerin +1785 Ni troguanidine ;+720 Triacetin --1284 Water 5 Theadvantages of the gas-producing compositions of this invention overpresently available formulations are readily apparent. The compositionsof this invention are characterized by distinguishing properties whichhave heretofore been found highly desirable but unobtainable, namely, avery low temperature coefficient of equilibrium pressure and asubstantially constant burning rate over a wide pressure range withinthe zone of useful rocket pressures. Although particular emphasis hasbeen placed on the desirability and advantages of the compositions ofthis invention when applied to jetactuated devices, it is to beunderstood that these compositions have a general utility inapplications where gasproducing charges are desired. They are especiallyadvantageous where substantially constant pressures are desired andwhere any rapid increase in pressure would be highly undesirable.

This application is a continuation-in-part of my copending applicationSerial No. 102,427, filed June 30, 1949, now abandoned.

' What I claim and desire to protect by Letters Patent is:

1. A gas-producing composition consisting essentially of a smokelesspowder having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% of atleast one material selected from the group consisting of lead, theinorganic compounds of lead and the aliphatic compounds of lead, saidgas-producing composition having a heat of explosion of not more than900 calories per gram and having a value of less than 0.7 for the slopen of the line representing the pressure-burning rate relationship.

2. A gas-producing composition consisting essentially of a smokelesspowder having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% oflead, said gas-producing composition having a heat of explosion of notmore than 900 calories per gram and having a value of less than 0.7 forthe slope n of the line representing the pressure-burning raterelationship.

'3. A gas-producing composition consisting essentially of a smokelesspowder having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% oflead oxide, said gas-producing composition having a heat of explosion ofnot more than 900 calories per gram and having a '11 value of less than0.7 for the slope n of the line representing the pressure-burning raterelationship.

4. A gas-producing composition consisting essentially of a smokelesspowder having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding of leadZ-ethyl hexoate, said gas-producing composition having a heat ofexplosion of not more than 900 calories per gram and having a value ofless than 0.7 for the slope n of the line representing thepressure-burning rate relationship.

5. A gas-producing composition consisting essentially of a smokelesspowder having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding of afatty acid salt of lead, said gas-producing composittlon having a heatof explosion of not more than 900 calories per gram and having a valueof less than 0.7 for the slope n of the line representing thepressure-burning rate relationship.

6. A gas-producing composition consisting essentially of a smokelesspowder having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% oflead stearate, said gas-producing composition having a heat of explosionof not more than 900 calories per gram and having a value of less than0.7 for the slope n of the line representing the pressure-burning raterelationship.

7. A gas-producing composition consisting essentially of a smokelesspowder containing from 85% to 95% of nitrocellulose and having uniformlyincorporated therein and intimately admixed therewith within eachparticle thereof an amount not exceeding 10% of at least one materialselected from the group consisting of lead, the inorganic compounds oflead, and the aliphatic compounds of lead, said gas-producingcomposition having a head of explosion of not more than 900 calories pergram and having a value of less than 0.7 for the slope n of the linerepresenting the pressure-burning rate relationship.

8. A gas-producing composition consisting essentially of a smokelesspowder containing from 85% to 95% of nitrocellulose and having uniformlyincorporated therein and intimately admixed therewith within eachparticle thereof an amount not exceeding 10% of lead, said gasproducingcomposition having a heat of explosion of not more than 900 calories pergram and having a value of less than 0.7 for the slope n of the linerepresenting the pressure-burning rate relationship.

9. A gas-producing composition consisting essentially of a smokelesspowder containing from 85 to 95% of nitrocellulose and having uniformlyincorporated therein and intimately admixed therewith within eachparticle thereof an amount not exceeding 10% of lead oxide, saidgas-producing composition having a heat of explosion of not more than900 calories per gram and having a value of less than 0.7 for the slopen of the line representing the pressure-burning rate relationship.

10. A gas-producing composition consisting essentially of a smokelesspowder containing from 85% to 95% of nitrocellulose and having uniformlyincorporated therein and intimately admixed therewith within eachparticle thereof an amount not exceeding 10% of lead 2-ethyl hexoate,said gas-producing composition having a heat of explosion of not morethan 900 calories per gram and having a value of less than 0.7 for theslope n of the line representing the pressure-burning rate relationship.

11. A gas-producing composition consisting essentially of a smokelesspowder containing from 85% to 95% of nitrocellulose and having uniformlyincorporated therein and intimately admixed therewith within eachparticle thereof an amount not exceeding 10% of a fatty acid salt oflead, said gas-producing composition having a 12 heat of explosion ofnot more than 900 calories per gram and having a value of less than 0.7for the slope n of the line representing the pressure-burning raterelationship.

12. A gas-producing composition consisting essentially of a smokelesspowder containing from to of nitrocellulose and having uniformlyincorporated therein and intimately admixed therewith within eachparticle thereof an amount not exceeding 10% of lead stearate, saidgas-producing composition having a heat of explosion of not more than900 calories per gram and having a value of less than 0.7 for the slopen of the line representing the presure-burning rate relationship.

13. A gas-producing composition, consisting essentially of a smokelesspowder containing nitrocellulose and at least one explosive nitric esterand having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% of atleast one material selected from the group consisting of lead, theinorganic compounds of lead, and the aliphatic compounds of lead, saidgas-producing composition having a heat of explosion of not more than900 calories per gram and having a value of less than 0.7 for the slopen of the line representing the pressure-burn ing rate relationship.

14. A gas-producing composition consisting essentially of a smokelesspowder containing nitrocellulose and at least one explosive nitric esterand having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% oflead, said gas-producing composition having a heat of explosion of notmore than 900 calories per gram and having a value of less than 0.7 forthe slope n of the line representing the pressure-burning raterelationship.

15. A gas-producing composition consisting essentially of a smokelesspowder containing nitrocellulose and at least one explosive nitric esterand having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% oflead oxide, said gas-producing composition having a heat of explosion ofnot more than 900 calories per gram and having a value of less than 0.7for the slope n of the line representing the pressure-burning raterelationship.

16. A gas producing composition consisting essentially of a smokelesspowder containing nitrocellulose and at least one explosive nitric esterand having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% oflead 2-ethyl hexoate, said gas-producing composition having a heat ofexplosion of not more than 900 calories per gram and having a value ofless than 0.7 for the slope n of the line representing thepressure-burning rate relationship.

17. A gasproducing composition consisting essentially of a smokelesspowder containing nitrocellulose and at least one explosive nitric esterand having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% of afattey acid salt of lead, said gas-producing composition having a heatof explosion of not more than 900 calories per gram and having a valueof less than 0.7 for the slope n of the line representing thepressureburning rate relationship.

18. A gas-producing composition consisting essentially of a smokelesspower containing nitrocellulose and at least one explosive nitric esterand having uniformly incorporated therein and intimately admixedtherewith within each particle thereof an amount not exceeding 10% oflead stearate, said gas-producing composition having a heat of explosionof not more than 900 calories per gram and having a value of less than0.7 for the 13 slope n of the line representing the pressure-burningrate 2,385,135 relationship. 2,498,388 2,982,638 References Cited in thefile of this patent UNITED STATES PATENTS 621,685

1,357,865 Henning Nov. 2, 1920 14 Holmes Sept. 18, 1945 Ball Feb. 21,1950 Cooley May 2, 1961 FOREIGN PATENTS Great Britain Apr. 14, 1949

1. A GAS-PRODUCING COMPOSITION CONSISTING ESSENTIALLY OF A SMOKELESSPOWDER HAVING UNIFORMLY INCORPORATED THEREIN AND INTIMATELY ADMIXEDTHEREWITH WITHIN EACH PARTICLE THEREOF AN AMOUNT NOT EXCEEDING 10% OF ATLEAST ONE MATERIAL SELECTED FROM THE GROUP CONSISTING OF LEAD, THEINORGANIC COMPOUNDS OF LEAD AND THE ALIPHATIC COMPOUNDS OF LEAD, SAIDGAS-PRODUCING COMPOSITION HAVING A HEAT OF EXPLOSION OF NOT MORE THAN900 CALORIES PER GRAM AND HAVING A VALUE OF LESS THAN 0.7 FOR THE SLOPEN OF THE LINE REPRESENTING THE PRESSURE-BURNING RATE RELATIONSHIP.